Blocks or pulleys are used in a variety of application, including tackle systems and on sailing vessels to control and change direction of lines. A standard block or pulley includes a line receiving sheave rotatably mounted between a pair of cheeks or side plates, with the cheeks extending in one direction beyond the sheave to provide a head for attachment of the block to other objects, or a support.
In a block used as a yacht fitting, a swivel post extends outwardly from the head, and a shackle is attached in an opening through the swivel post. The swivel post is rotatably mounted in the head, in order to allow the block to rotate and accommodate a changing angle of a line. In other situations, the swivel post is fixed in position by use of a set screw in the head in engagement with the swivel post as shown in U.S. Pat. No. 3,528,645. The set screw may be engaged and disengaged as required, but this requires the use of a screwdriver and possible loss of the set screw.
There is a continuing need to provide simplification and convenience features on yacht fittings in order to improve operations and changes under sailing conditions without sacrifice of reliability.